Governor



Patented June 1, 1948 GOVERNOR Robert E. Boyden,

Drake, Glendale,

Multiplier Corporation, n corporation of Californi Application November26, 1945, Serial No. 630,914

-7Claima.

This invention relates to speed governors and has particular referenceto governors for maintaining electric motors at substantially constantspeed under varying load conditions.

Heretoi'ore, governors of the above type have generally utilized thedifferential action between centrifugal force acting on a governor flvws and a restraining force in the form of a spring to control the speedof an electric motor by opening and closing the switch contacts in themotor circuit by amounts in proportion to the diiilerential actionproduced.

Also, in the last several years governor manufact'urers have tended toreduce the mass of the flyweights or similar centrifugally operatedcontrol means in order to reduce the lag in control introduced by theinertia and momentum of such parts. At the critical control speed ofgovernors of such types, the small amount of movement of the flyweightmass necessary to open and close the contacts in order to control thespeed, and the relatively small amount of mass available to cause acontrolling action, introduced a detrimental arcing eflect since thecontacts are separated only slightly. This arcing effect is accentuatedby reason of the fact that since even the maximum separation of thecontacts is only a minute amount, the are thus produced still maintainsa considerable current carrying capacity. As a result the contacts,instead of completely closing, tend to merely create an arc and thenvary the resistance of the are by varying the separation of the contactpoints. Such arcing necessitates arc damping means such as condensers,etc. to reduce as far as possible the tendency of the contact points toare. Furthermore, such arcing causes loss in electrical power and radiointerference as well as deterioration of the contacts.

It therefore becomes the principal object of the present invention toreduce arcing in a motor governor.

A further object of the invention is to obviate the necessity of acondenser or other are damping means for a motor governor.

A further object is to reduce radio interference due to a motorgovernor.

A further object is to reduce electric power losses in a governor.

A further object is to preduce the frequency at which the contacts of agovernor are operated whereby to prolong the life of the contact points.

A further object is to provide an arrangement of governor elementswhereby the frequency of switch contact action is automaticallyregulated Los Angcles, and Edward P.

Calif., ass

inner: to Clary Los Angeles, Calif., a

so that when the motor is runmng idle a minimum frequency of contactaction is obtained to decrease contact deterioration and when the motoris running under load the frequency of contact action is automaticallyincreased to maintain a substantially uniform motor speed.

A further object of the invention is to provide a simple and compactgovernor which is inexpensive to manufacture.

The manner in which the above and other objects of the invention areaccomplished will be readily understood on reference to the followingspecification when read in conjunction with the accompanying drawing;

Fig. 1 is a side view partly in section, of an electric motor governorembodying the present invention.

Fig. 2 is a front view of the motor governor and is taken along the line2-2 of Fig. 1.

Fig. 3 is a transverse sectional view of the flyweight unit and is takenalong the line 33 of Fig. l.

Fig. 4 is a sectional view of a modified form of fiyweight unit.

Fig. 5 is a sectional view through the governor switch arrangement andis taken along the line 5-5 of Fig. 2.

Fig. 6 is a schematic diagram of an exemplary circuit showing theconnection of the motor governor to an electric motor.

Fig. 7 is a modified form of switch which may be incorporated in thegovernor of the present invention.

Referring to the drawing, the governor, generally indicated at I 0, isillustrated as comprising a. main bracket ll attached by screws l2 (Fig.2) to the end casing of a. motor iii.

The flyweight unit of the governor comprises a hub H attached by a pini5 to the armature shaft it of the motor. A fiyweight bracket H- issecured to the hub and has mounted thereon on diametrically opposedsides of the motor shaft, a pair of transversely extending pins l8 whichpivotably support fiyweight levers IQ for movement about axes extendingto right angles to the axis of rotation of the flyweight unit. A ball20, freely movable in an axially extending hole in the hub i4, isadapted to be forced along the axis of the motor by the tails of thelevers l9.

It will be noted that the center of gravity of each of the levers i9lies to the right (Fig. 1) of its pivotal axis so that, as the motoraccelerates, the tails of the levers l9 force the ball 20 outwardlyagainst an car 22 located at one end of a lever 2|. The latter ispivoted on a pin 23 (Figs. 1

and 2) securely mounted on an upturned ear of the main bracket II. Ancar 24 on the lower end of lever 2| overlies a plunger 25 (Fig. of aswitch generaly indicated at 26. 1

The switch 26 comprises a body 21 of insulating material attached byscrews 23 to the bracket II. A leaf spring 29 of electrically conductivematerial is attached at one end by a screw 30 to an electric terminalwhich is connected by screw 3| to a conductor 32. At its free end 29,the leaf spring has a contact I30 normally engaging a stationary contact33 secured as by screw 34 to a second terminal to which is attached asecond conductor 36.

The spring 23 comprises a main section 31 which extends from the screw30 and is biased toward the contact 33. One or more toggle sections 33of the spring are integrally formed or attached at 39 to the mainsection and are bowed under compression, being held at their free endsby a inlcrum block 33 which is also held in place by the screw 30.

It will be noted that the fulcrum points of the toggle sections 38 arenormally below a line passing through the point 33 and the point ofattachment of the spring to thescrew 30. Thus, the vertical component offorce (as viewed in Fig. 5) exerted by the toggle section 33 normallyaids the biasing effect of the main section 31 to press the spring intointimate engagement with the contact 33. Whenever the plunger 25 ispressed inwardly against the action of the main portion 31, the latterwill move downward against its own biasing effect as well as against thetoggle action of sections 38 until the section 31 passes below thefulcrum point of section 38. At that time, the toggle sections 38 willexert their vertical component of force in a downward direction, aidingthe plunger 25. However, the downward component of force is notsufficient to overcome the upward biasing effect of the section 31 sothat upon release of pressure upon the plunger 25 the contact springwill assume its normal closed condition illustrated in Fig. 5.

The above described switch is commercially known and available under thename microswitch, being disclosed-and claimed in the patent to P. K.McGall, Number 1,960,020. However, it is to be understood that othertypes of switches operating under the same basic type of toggle actionmay be employed without departing from the scope of the presentinvention.

It will be seen from the above that as the speed of the motor approachesa definite amount, the flyweight levers I9 will rock about their axes,pressing the ball 20 outward to rock lever 22 and thereby cause theplunger 25 to press downward against the spring section 31. As the forceagainst the spring section 31 increases, it will gradually overcome thebias effect of the spring as well as the force exerted by the togglesections 38 and will finally force the spring into a lowermost position,breaking the circuit. This final action will occur in an abruptmovement, thus reducing the tendency of an arc to form between thecontacts. As the speed of the motor is reduced due to breaking of thecircuit between the contacts the reduction of centrifugal forcedeveloped by the flyweight levers I3 will permit the spring 31 to againassume its closed position. This closing action of the spring will againoccur in an abrupt movement due to the toggle action of the springsection'38.

Means are provided for adjusting the governor to control the speed ofthe motor as desired.

- Referring to Fig.

1 an adjusting screw 40 is threaded in a collet 4| integrally attachedto the bracket II. Located between the ends of screw 40 and the ear 22of lever 2| is a compression spring 42 which may be adjusted by thescrew to aid the spring section 31 in opposing the action of thefiyweight levers. the motor may be increased by increasing the pressureof the spring 42 against the lever 2|, requiring greater centrifugalforce to be developed in the fiyweight levers by virtue of a higherrotational speed in order to open the switch contacts.

A spring 44 is inserted between the ear 22 of lever 2| and the bracketII to oppose the spring 31 so that the screw 40 may be adjusted toefffect either an aiding or opposing action upon the biasing springsection 31 to vary the controlling,

speed of the motor throughout a relatively wide range of speed.

It will be noted that the spring 44 is considerably weaker than thecompression spring 42 since the former is utilized during control of thegovernor at relatively low speeds wherein the centrifugal forcedeveloped by the fiyweight levers is correspondingly weaker. Thiscombination of springs results in a more uniform control throughout thevarious possible speed ranges of the motor.

During operation of the motor and governor under no-load conditions theswitch contacts are opened and closed at a relatively low frequency,such frequency being dependent upon the amount of revoluble mass orflywheel effect of the motor armature and other rotatable partsconnected thereto. However, under load conditions, this frequency isincreased and such increase is proportional to the increase in load.This feature results in a, considerable saving in contact deterioration.

Fig. 6 illustrates an exemplary connection of the governor to the motor,the latter being illustrated as of the series type comprising a fieldwinding I3a and an armature I3b connected in series with the contacts 33and I30. A resistance 45 may be shunted across the contacts to reducethe voltage drop during opening and closing of the contacts. The latteris illustrated in Figs. 1 and 2 as being supported in the governor unitby cars 46 extending from the brackets II.

Fig. '7 illustrates a modified form of switch which may be used in lieuof the switch 23 (Fig. 5). This switch comprises a base 21a ofinsulating material to which is attached, by a screw I40, a flexibleterminal I35. The forward end of the terminal is biased downward aslight amount and carries a contact 33a. A second contact I30a ismounted on a pivotal piece |3| fulcrumed on a pivot block 39a suitablyattached to the base 210.,

the block 390. also forming the second terminal for the switch. Abiasing spring I32 is tensioned between the base and the piece I3I tonormally hold the contacts in closed condition.

A spring I33 is tensioned between the block 39a and the outer portion ofthe piece I3I to exert a toggle action on the piece. That is, in theclosed condition of the switch, as illustrated in Fig. 7, the centerline of the spring I33 extends above the fulcrum point of the piece I3I,thus exerting an upward force, aiding the spring I32.

When the piece I3I is forced downward by a plunger 25a. the flexibleterminal I35 will cause contact 33a to follow the contact I300 until thepiece I3I moves to a position wherein the center line of spring I33passes below the fulcrum point of the piece. The contact I30a will nOWleave Thus, the speed of Y Contact 33a in a somewhat abrupt manner inview of the reversal of the action of spring I". Although the spring I33will now oppose the tension of spring I32 it will not quite overcome thelatter so that when pressure on plunger 25a is released the switch willreassume its closed condition. A limit stop may, if desired, be providedto prevent downward movement of the piece "I beyond a definite limit.For this p pose, a foot ill formed on the lower end of the terminal I"may be extended laterally to limit downward movement of the piece l3l.

Fig. 4 illustrates a modified form of flyweight unit in which thecontrolling efiect of the flyweight levers l9 may be adjusted. In thisfigure all elements similar to those shown in Fig, 1 are indicated bythe same reference numerals. Threadably attached to the outer ends ofthe flyweight levers l9 are adjustable screws 41. By adjusting thescrews 41 outwardly a greater amount of centrifugal force is developedand therefore a more positive control action is effected by theflyweight levers. The provision of this adjustment enables a minimumflyweight mass to be used whereby to obtain a readily responsivecontrolling action while at the same time providing a governor whichwill be efi'ective over a wide range of speed, particularly at low speedsince the centrifugal force developed in any rotatable body isproportional to'the square of the speed of such body.

We claim:

1. A motor speed control device, comprising: electric contact means forcontrolling a circuit to a motor, said contact means being movablebetween open and closed positions, spring meansnormally holding saidcontact means in closed position, a governor device adapted to berotated by said motor and including means displaceable by centrifugalforce during rotation thereof for opening said contact means; asnap-over spring means coacting, in a first position thereof, with saidfirst-mentioned spring means, to close said contact means, meansoperable by said displaceable means upon a predetermined displacementthereof by centrifugal force for causing said snap-over spring means tomove from said first position to a second position, said snap-overspring means being effective to substantially abruptly move between saidtwo-mentioned positions, a third spring means opposing the action ofsaid first-mentioned spring means and aiding 6 eratively connected tosaid dispiaceable means,

and means for adjusting the eflective force of said said governor deviceand said second spring.

means in opening said contact means, and means for adjusting theeffective force of said third spring means.

2. A motor speed control device, comprising: electric contact means forcontrolling a circuit to a motor, said contact means being movablebetween open and closed positions, spring means normally holding saidcontact means in closed position, a governor device adapted to berotated by said motor and including means displaceable by centrifugalforce during rotation thereof for opening said contact means; asnap-over spring means coacting, in a first position thereof, with saidfirst-mentioned spring means, to close said contact means, meansoperable by said displaceable means upon a predetermined displacementthereof by centrifugal force for causing said snap-over spring means tomove from said first position to a second position to open said contactmeans, said snap-over spring means being eilective to substantiallyabruptly move between said two-mentioned positions, third spring means01)- spring means to selectively aid or oppose said governor device. 3.In an electric motor governor having electric contact means for thecircuit of said motor, said contact means being movable between open andclosed positions, and a governor device adapted to be rotated by saidmotor and including means displaceable by centrifugal force duringrotation thereof; a leaf spring supported in cantilever fashion adjacentone end thereof and adapted to flex at the other end thereof to open andclose said'contact means, a spring strip connected at one end to theflexible end of said leaf spring, said spring strip being bowed inlongitudinal compression and being pivoted at the other end thereof at apoint between the ends of said leaf spring, said leaf spring normallyassuming a position on one side of the dead center of the springassemblyformed by said leaf spring and said spring strip whereby to close saidcon tact means, means operable by said displaceable means upon apredetermined displacement thereof by centrifugal force for acting onsaid leaf spring between said point of support thereof and said pivotpoint of said spring strip, whereby to cause said spring assembly toopen said contact means with a snap action, a second spring meansoperatively associated with said spring assembly for exerting a biasingeffect thereon, and means for adjusting the force of said second springmeans to selectively either aid or oppose the action of said device andthereby affect the action of said spring assembly in opening and closingsaid contact means throughout the range of movement thereof.

4. A motor speed control device comprising: a bracket adapted to besecured in fixed relation to a motor; a centrifugal governor adapted tobe driven by said motor and including flyweight means responsive tocentrifugal force; a normally closed switch mounted upon said bracket; alever; means .pivotally mounting said lever upon said bracket at a pointintermediate the ends of said lever, one arm of said lever beingengageable with said switch for actuating said switch to its openposition; a spring connected with the other arm of said lever andcontinuously biasing said lever in a direction tending to allow openingof said switch, said other arm being operable by said nyweight means toactuate said lever in the same direction as said spring; and a. secondspring acting on said lever yieldably opposing the force of saidflyweight means and tending to actuate said lever in a direction toallow closing of said switch.

5. A motor speed control device comprising: a bracket adapted to besecured in fixed relation to a motor; a centrifugal governor adapted tobe driven by said motor and including fiyweight means responsive tocentrifugal force; a normalby closed switch mounted upon said bracket; alever; means pivotally mounting said lever upon said bracket at a pointintermediate the ends of said lever, one arm of said lever beingengageable with said switch for actuating said switch to its openposition; a spring connected with the other arm of said lever andcontinuously biasing said lever in a direction tending to allow openingof said switch, said other arm being operable by said fiyweight means toactuate said lever in the same direction as said spring; a second springacting on said lever yieldably opposing the force of said flyweightmeans and tending to actuate said lever in a direction to allow closingof said switch; and means carried by said bracket for adjusting theforce of said second spring.

6. A motor speed control device comprising: a bracketadapted to besecured in fixed relation to a motor; electric contact means forcontrolling a circuit to said motor and mounted on said bracket, saidcontact means being movable between open and closed positions; springmeans normally holding said contact means in closed position; acentrifugal governor adapted to be driven by said motor and includingmeans displaceable by centrifugal force during rotation thereof a lever;means pivotally mounting said lever upon said bracket at a pointintermediate its ends; one arm of said lever being operable by saiddisplaceable means to cause the other arm thereof to move said contactmeans to open position; a snap-over spring means coacting, in a firstposition thereof,, with said first-mentioned spring means to close saidcontact means, and coacting, in a second position thereof, with saiddisplaceable means upon a predetermined displacement thereof to opensaid contact means, said snap-over spring means being effective tosubstantially abruptly move between said twomentioned positions; aspring connected between said lever and said bracket and continuouslybiasing said lever in a direction tending to open said contact means; asecond spring acting on said lever yieldably opposing the force of saiddisplaceable means and said first-mentioned spring; and means carried bysaid bracket for adjusting the force of said second spring.

7. A motor speed control device, comprising: electric contact means forcontrolling a circuit from said first position to a second position,said snap-over spring means being effective to substantially abruptlymove between said twomentioned positions, a third, spring means'opposingthe action of said first-mentioned spring means and aiding said governordevice and said second spring means in opening said contact means, and aweight element carried by said flyweight means and adjustable relativethereto to vary the centrifugal force efiective during rotation of saidfiyweight means.

ROBERT E. BOYDEN. EDWARD P. DRAKE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date McGall May 22, 1934 Warner Nov. 5, 1940Number

